The use of orbiting vehicles for carrying out various types of missions in space has been the subject of intense research and development activity in the past couple of decades. This activity has led to the space shuttle system that is currently in use. As is well-known, the current system is a vertical takeoff system in which a transatmospheric shuttle vehicle is mounted piggyback on booster rockets for takeoff and launch. This system has had considerable success and has accomplished a number of missions. However, vertical takeoff systems in general and the current shuttle system in particular have a number of serious limitations.
The problems associated with vertical takeoff systems include the need for complex, extremely heavy, and expensive ground support equipment in order to accomplish takeoff. Such equipment is necessary, for example, in order to handle the large vertically oriented booster stage and to accomplish the cumbersome process of mounting the orbiter vehicle up onto the booster stage in piggyback fashion. The need for such equipment results in very high launch costs and therefore a high cost for each of the missions performed by the orbit vehicle. In addition, such equipment is provided at only a very few highly specialized ground installations. This severe limitation on the choice of launch sites results in corresponding limitations on flexibility in the system in terms of obtainable orbits and/or times of launching.
Known vertical takeoff systems, such as the Space Shuttle, are also subject to the problem of nonreusability of portions of the booster structure. For example, some structural elements such as fuel tanks, are discarded at orbit altitude and cannot be recovered. The nonrecoverability and consequent total nonreusability of such elements adds significantly to the cost of the system since the total cost of such elements is a recurring cost that is fully experienced each time the orbit vehicle is launched. Other elements of the booster structure are recoverable but are reusable only in a limited sense since they generally require time consuming and expensive refurbishment. Therefore, only part of the cost of such recoverable elements is nonrecurring from launch to launch. The recurring portion of the cost of such recoverable elements further adds to the overall cost of the system.
Other problems associated with vertical takeoff systems include operational limitations that severely restrict the flexibility of such systems. The turn around time, or the time between launches, is quite long because of the need to recover and refurbish the recoverable booster structure and the relatively long time required to make all the preparations necessary for a vertical takeoff. These preparations include readying and positioning the booster stage and mounting the orbiter stage onto the booster stage. In addition to greatly extending turn around time, the long launch preparation time makes it virtually impossible to accomplish a launch on short notice.
The operational limitations also include severe limitations on the orbits that may be obtained from a given launch site without incurring unacceptable penalties. Such penalties include a great loss in time in waiting for the ground track of an orbiting structure that is to be intercepted by the transatmospheric vehicle to pass over the launch site. Efforts to avoid time penalties by providing the transatmospheric vehicle with significant orbit maneuver capabilities lead to the penalty of decreased payload capacity because of the need for the orbitor to carry with it into orbit a significantly increased amount of fuel. Such losses in payload capacity are generally prohibitive, and therefore, maneuvering in orbit is not a practical solution to the problem of providing orbit flexibility. The problem is further aggravated by the fact that orbits of inclination less than the launch latitude cannot be reached at all for most systems without an orbit plane change maneuver.
The time limitations of vertical takeoff systems--the long turn around and launch preparation times--can be tolerated in nonemergency situations in which a mission may be planned well in advance. However, emergency situations, such as those in which persons in orbit are in need of rescue or a military mission must be accomplished very quickly, the time restrictions of vertical launch systems are unacceptable. In order to provide the capability for adequately dealing with such emergency situations, there is a great need for a launch system in which preparations for a launch may be made on very short notice, a target orbit may be attained without time or weight penalties, and any necessary second and subsequent launchings may be accomplished fairly rapidly. Such quick launch and turn around capabilities and flexibility in obtainable orbits would also serve to reduce the cost of the launch system relative to both emergency and nonemergency missions.
Various concepts for horizontal takeoff launch systems have been suggested. These concepts avoid most of the problems associated with vertical takeoff systems, but have other problems associated with their proposed implementation. In general, these concepts cannot be made truly operational by use of existing technology. Therefore, the expected development costs of systems based on these concepts are quite high and dates of completion of operational systems would be relatively far into the future. Another problem associated with suggested horizontal takeoff concepts is the inability to meet the ever present need for a "positive" payload. For a launch system to be capable of providing a positive payload, it must be capable of launching into orbit a gross weight that is greater than the weight of the orbiter vehicle itself plus the fuel required by the orbiter vehicle. The gross weight minus the combined vehicle and fuel weight is the potential payload. In a fully operational practical launch system, the potential payload is not only positive but is also above a practical minimum. Finding a solution to the problem of providing a horizontal takeoff system capable of launching a positive payload that equals or exceeds a practical minimum has proved very difficult but is crucial to the success of any such system.
U.S. Pat. Nos. 3,702,688, granted Nov. 14, 1972, to M.A. Faget, and No. 4,265,416, granted May 5, 1981, to L.R. Jackson et al each disclose a system for launching a space shuttle type vehicle. The system disclosed by Faget is a two stage vertical takeoff system in which the shuttle vehicle is mounted on the booster vehicle in piggyback fashion. Faget describes the booster vehicle as being provided with air breathing auxiliary engines that are started after the booster attains a normal subsonic flight attitude following staging. The booster is than recovered by means of a conventional horizontal wheel landing. Upon completing its mission, the orbiter reenters and lands in a manner similar to the booster vehicle.
The launch system disclosed by Jackson et al is a horizontal takeoff and landing system. The system includes an orbit vehicle and two smaller booster vehicles. These booster vehicles are releasably connected to the underside of the two halves of the delta wing of the orbiter vehicle. Each connection is accomplished by means of a pylon that extends upwardly from the booster and is attached to the orbiter vehicle by exploding bolts. The boosters are unmanned and radio controlled. The lift required to ascend to the staging altitude is provided by the wings of both the orbiter and the booster vehicles.
The patent literature also includes proposals for linking two space vehicles. In U.S. Pat. No. 3,289,974, granted Dec. 6, 1966, C.B. Cohen et al disclose a two stage orbit vehicle. This vehicle consists of a delta wing aircraft that is nested into the top of a pod that provides space for crew movement and payload equipment during orbit and a heat shield for the aircraft during reentry. The two stages separate following reentry and prior to landing. Telescoping rods eject the aircraft from the pod. The aircraft makes a conventional wheel landing, and the pod descends by parachute. U.S. Pat. No. 3,753,536, granted Aug. 21, 1973, to N. White discloses a mechanism for coupling two orbiting space vehicles. A larger carrier vehicle extends an annular coupling from a hold in its body. The vehicle to be carried moves into engagement with the annular coupling and then is swung down into the hold of the carrier vehicle.
In U.S. Pat. No. 2,368,288, granted Jan. 30, 1945, K.W. Couse et al disclose a system in which supply units, such as ground vehicles, are attached to a dual fuselage aircraft for transport by the aircraft. A ground vehicle to be transported is separated into forward and aft portions which are rolled into contact with the forward and aft portions, respectively, of the center wing of the aircraft. Each half of the ground vehicle has a slot therein which receives a portion of the center wing. When the two halves have been rolled into position surrounding the wing, the two halves are secured together and take on the appearance of a third fuselage.
U.S. Pat. Nos. 3,227,399, granted Jan. 4, 1966, to J. Dastoli et al, and 3,999,728, granted Dec. 28, 1976, to G. F. Zimmer each disclose a composite aircraft configuration in which an escape capsule or compartment is integrated into a top portion of the main part of the aircraft. In the Dastoli configuration, the detachable compartment forms the upper portion of the fuselage of the complete aircraft. The compartment is provided with retractable helicopter blades, and a hydraulic release allows the compartment to move upwardly. The Zimmer escape capsule forms the cabin and part of the leading edges the wings of the complete aircraft. The capsule is separated by means of rockets that are carried by the capsule and are directed toward the main portion of the aircraft to provide an ejection force.
A number of other examples of composite aircraft configurations can be found in the patent literature. These configurations have purposes such as launching an aircraft, providing an escape, and transporting cargo. U.S. Pat. Nos. 2,009,296, granted Jul. 23, 1935, to R. H. Mayo, 2,364,803, granted Dec. 12, 1944, to P. Mayhew, and 3,070,326, granted Dec. 25, 1962, to A. A. Griffith each disclose a configuration in which one aircraft is launched from a position on top of another aircraft. U.S. Pat. Nos. 2,883,125, granted Apr. 21, 1959, to A. J. Jarvis et al, 2,998,208, granted Aug. 29, 1961, to J. Di Perna, and 3,006,576, granted Oct. 31, 1961, to E. A. Elijah each disclose a configuration in which an escape aircraft is mounted on top of another aircraft. N. L. Crook discloses a configuration in which a separate payload aircraft is carried suspended from a control aircraft in U.S. Pat. Nos. 3,258,228, granted Jun. 28, 1966, and 3,516,624, granted Jun. 23, 1970. Configurations in which a subservient aircraft is carried within and deployed from an interior compartment of a primary aircraft are disclosed in U.S. Pat. Nos. 3,567,156, granted Mar. 2, 1971, to D. L. Bauer, and 3,703,998, granted Nov. 28, 1972, to P. F. Girard. U.S. Pat. Nos. 2,876,677, granted Mar. 10, 1959, to J. R. Clark et al, and 3,000,593, granted Sept. 19, 1961, to G. Eggers et al each disclose a configuration in which a body such as a missile or a drone is mounted on a wing of an aircraft. U.S. Pat. No. 3,419,234, granted Dec. 31, 1968, to A. G. Poirier discloses a system in which a rescue aircraft lowers a coupling that engages the top of a damaged aircraft to transfer people from the damaged aircraft to the rescue aircraft. U.S. Pat. Nos. 2,981,499, granted Apr. 25, 1961, to R. B. Janney II, and 4,267,987, granted May 19, 1981, to W. R. McDonnell each disclose a system in which one aircraft is used to assist another aircraft in taking off. The Janney patent discloses a catapult launch vehicle that engages the underside of the vehicle to be launched. The McDonnel patent discloses a system in which an airborne helicopter engages the top of an airplane to enable the airplane to take off either vertically or with a very short ground run.
U.S. Pat. No. 2,399,217, granted Apr. 30, 1946, to D. S. Fahrney discloses a system in which smaller aircraft are mounted to underside portions of the wings or belly of a carrier glider for transport. An aircraft is lifted into and lowered from its stowed position by a cable and pulley arrangement that operates a trapeze. U.S. Pat. No. 2,621,000, granted Dec. 9, 1952, to R. A. Robert discloses a system in which a high speed aircraft is linked to a carrier aircraft and is launched from the carrier aircraft. In the launch procedure, the speed of the carrier engine is increased and the power of the high speed aircraft is simultaneously adjusted, and then the locking device that secures the two aircraft together is released to allow the high speed aircraft to separate from the carrier under its own power at a lower speed than the carrier. The two aircraft may be linked in flight for refueling the smaller high speed aircraft. U.S. Pat. No. 4,451,017, granted May 29, 1984, to W. R. Marshall discloses a three stage rocket vertical launch vehicle in which propellants are fed from one stage to another to enable the vehicle to parallel stage its use of engines and components.
U.S. Pat. No. 2,481,542, granted Sept. 13, 1949, to G. L. Schuyler discloses a device for displacing a projectile from a bomb bay a safe distance before the projectile is allowed to fall freely or is ignited. The projectile is attached to the forked outer ends of displacing arms by attaching pins. The inner ends of the displacing arms are pivotably mounted to the fuselage within the bomb bay. The projectile is pivotably moved into a lowered position by a cable mechanism or by the action of gravity. Following the lowering of the projectile, the latching pins are released and then the projectile is ignited.
West German Pat. No. 2,306,811, granted to E. Foell, and laid open on Aug. 14, 1974, discloses a composite aircraft in which a carrier aircraft has a fuselage and wings that define a free space for receiving a carried flight device. The outside surfaces of the flight device complement the shaping of the carrier aircraft and at least partially increase the carrier's lift surface. In one embodiment, shown in FIG. 4 of the Foell patent, the front section of the flight device fits into and "grips" the fuselage of the carrier. The carrier has a relatively short fuselage and strongly swept-back wings. The flight device completes the wings of the carrier into a delta wing.
Launching systems for shuttle craft are disclosed in an article by Curtis Peebles, entitled "Air-Launched Shuttle Concepts" , in the April 1983 issue of the Journal of the British Interplanetary Society, Vol. 36, No. 4. Each of the shuttle concepts discussed in the article include a first stage aircraft capable of taking off from a conventional runway and a second stage that goes into orbit after separation. A Soviet system is described as having a high speed separation in the order of Mach 6 or 7. The article also describes a U.S. Air Force proposal having a modified Boeing 747 launch vehicle and a "comparatively low" separation altitude and velocity. With regard to separation velocity, it should be noted that the Jackson et al. patent cited above describes a system in which the separation velocity is about Mach 0.8, and Jackson et al. also mention that separation velocities in the range of Mach 2 to Mach 3.5 would require higher development costs but would yield lower recurring operating costs.
The known systems and the patents discussed above and the prior art cited in such patents should be carefully considered in order to put the present invention into proper perspective relative to the prior art.